IOS Intro - NSDictionary and NSMutableDictionary

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NSDictionary、NSMutableDictionary的基本用法

1.不可變詞典NSDictionary

字典初始化

NSNumber *numObj = [NSNumber numberWithInt:100];

以一個元素初始化

NSDictionary *dic = [NSDictionary dictionaryWithObject:numObj forKey:@"key"];

初始化兩個元素

NSDictionary *dic = [NSDictionary dictionaryWithObjectsAndKeys:numObj, @"valueKey", numObj2, @"value2",nil];

初始化新字典，新字典包含otherDic

NSDictionary *dic = [NSDictionary dictionaryWithDictionary:otherDic];

以檔案內容初始化字典

NSDictionary *dic = [NSDictionary dictionaryWithContentsOfFile:path];

 

常用方法

擷取字典數量

NSInteger count = [dic count];

通過key擷取對應的value對象

NSObject *valueObj = [dic objectForKey:@"key"];

將字典的key轉成枚舉對象，用於遍曆

NSEnumerator *enumerator = [dic keyEnumerator];

擷取所有鍵的集合

NSArray *keys = [dic allKeys];

擷取所有值的集合

NSArray *values = [dic allValues];

 

2.可變數組NSMutableDictionary

初始化一個空的可變字典

NSMutableDictionary *dic2 = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"v1",@"key1",@"v2",@"key2",nil];

NSDictionary *dic3 = [NSDictionary dictionaryWithObject:@"v3" forKey:@"key3"];

向字典2對象中添加整個字典對象3

[dic2 addEntriesFromDictionary:dic3];

向字典2對象中最佳一個新的key3和value3

[dic2 setValue:@"value3" forKey:@"key3"];

初始化一個空的可變字典

NSMutableDictionary *dic1 = [NSMutableDictionary dictionary];

將空字典1對象內容設定與字典2對象相同

[dic1 setDictionary:dic2];

將字典中key1對應的值刪除

[dic1 [email protected]"key1"];

NSArray *array = [NSArray arrayWithObjects:@"key1", nil];

根據指定的數組（key）移除字典1的內容

[dic2 removeObjectsForKeys:array];

移除字典所有對象

[dic1 removeAllObjects];

 

遍曆字典

快速枚舉

for (id key in dic){

     id obj = [dic objectForKey:key];

     NSLog(@"%@", obj);

}

一般枚舉

NSArray *keys = [dic allKeys];

inr length = [keys count];

for (int i = 0; i < length；i++){

     id key = [keys objectAtIndex:i];

     id obj = [dic objectForKey:key];

     NSLog(@"%@", obj);

}

通過枚舉類型枚舉

NSEnumerator *enumerator = [dic keyEnumerator];

id key = [enumerator nextObject];

while (key) {

        id obj = [dic objectForKey:key];

        NSLog(@"%@", obj);

        key = [enumerator nextObject];

}

IOS Intro - NSDictionary and NSMutableDictionary